1. Field of the Invention
The invention concerns an apparatus for mechanically decapitating fish which are conveyed transversely to their longitudinal axis and lying on one of their sides in receiving troughs of a trough chain, by means of a beheading or decapitating tool which is arranged closely beside one end of the receiving troughs and consists of a pair of rotatingly driven circular knives which are arranged symmetrically to each other, include an angle with each other and are aligned by their plane of symmetry to be nearly parallel to the plane of a bottom surface of the receiving troughs, as well as a pair of feeler rails which are arranged symmetrically to the plane of symmetry of the circular knives and displaceable synchronously by the fish against the force of a spring.
2. Description of the Prior Art
A beheading apparatus of that kind is known from German Letters Patent No. 11 28 617. In this device, a co-ordination of the planes of symmetry of the fish, of the feeler rails termed as gill guides in that publication, and the beheading knives takes place independently of the thickness of the respective fish thereby, that at least the smaller fish are raised from their support by means of the lower of the two gill guides in the region of the beheading cut to be performed. This is achieved in consequence of the synchronisation of the gill guides in the alignment of their plane of symmetry in that of the beheading knives through the lower guide. Each trough is provided with a conveying shoulder which supports the fish at its spine and is constructed to be fitting this. During the positioning of the fish by means of the gill guides, the fish, by reason of the frictional resistance at the guide edges of the gill guides and after engagement of the beheading knives additionally through their cutting resistance, is pressed against the conveying shoulder and is located there in respect of its height position in consequence of the prismatic construction of the conveying shoulder. By reason of this location of the spine, the fish in the course of its alignment tends to rotate, for which its back line forms the rotational axis. Beyond that, the retention of the fish merely in the gill guides has the effect that the remaining fish body sags downwardly. An exact symmetrical cut guidance of the wedge-shaped decapitating cut is therefore not to be attained for most of the fish sizes to be processed. This, however, is a pre-requisite for an economical cut guidance, for which it should nevertheless be made certain that undesired components, such as bone remnants, which could obstruct further mechanical processing or the removal of which requires additional work effort, are cut off with the head.
From the DD-PS No. 128 669 there is known a further decapitating apparatus, in which the fish, seized conveyingly by means of entraining members, slide transversely to their longitudinal axis on a support surface. In the region of decapitating knives performing a wedge-shaped cut, the fish runs between a pair of synchronised head guides. Support elements engaging through the support surface are connected with the lower one of the head guides. This has the effect that the fish is aligned by its plane of symmetry to that of the wedge-cut beheading knives in correspondence with the respective setting of the head guides determined by the thickness of the fish. Although the disadvantageous sagging of the fish body is thereby avoided, the remaining recited defects are, however, also to be found in this known device.
3. Object of the Invention
It is an essential object of the invention to provide a decapitating apparatus for fish, which makes a wedge-shaped decapitating cut extending exactly symmetrically to the plane of symmetry of the fish and thus an extremely economical decapitation possible.